hopefully centerfire, rimfire 25 auto is obsolete and really hard to find. Look the the breech face. if there is a hole in the center, then it a center fire. If the pin hole is at the top of the breech face then it a rimfire. IIRC they were 25 auto centerfire. 25 rimfire was made by stevens and stevens is the only company that made guns for the 25 rimfire and they were all rifles.